1. Field of the Invention
The present invention relates to a solid oxide fuel cell.
2. Description of the Related Art
(A power generation part of) a solid oxide fuel cell (SOFC) is formed by sequentially laminating a fuel electrode, an electrolyte film formed of a solid electrolyte, and an air electrode. In (the power generation part of) the SOFC, a difference in electric potential between the fuel electrode and the air electrode is generated based on a difference in oxygen potential between both surfaces of the electrolyte film by supplying a fuel gas (e.g., hydrogen gas) to the fuel electrode and supplying a gas containing oxygen (e.g., air) to the air electrode.
In the SOFC, an interconnector(s) (conductive connecting member(s) for current collection) is/are generally provided so as to be electrically connected to any one or both of the fuel electrode and the air electrode. Power based on the difference in electric potential is output via the interconnector(s).
With regard to the SOFC provided with an interconnector as described above, Japanese Patent No. 4146738 describes an SOFC in which an interconnector formed of dense conductive ceramics is provided on a fuel electrode and a conductive film formed of a P-type semiconductor is provided on the surface of the interconnector. The literature describes that, when the conductive film formed of a P-type semiconductor is provided on the surface of the interconnector, a current can be allowed to flow efficiently (i.e., an improvement in conductivity is achieved), although the reason for this is unclear.